Arthroscopic devices and methods

ABSTRACT

An arthroscopic system includes a re-useable, sterilizable handle integrated with a single umbilical cable or conduit. The single umbilical cable or conduit carries electrical power from a power and/or control console to the handle for operating both a motor drive unit within the handle and delivering the RF power to a disposable RF probe or cutter which may be detachably connected to the handle. The RF power delivered to the handle and on to the probe or cutter is typically bi-polar, where the handle includes first and second electrical bi-polar contacts that couple to corresponding bi-polar electrical contacts on a hub of the disposable RF probe or cutter is connected to the handle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Provisional Application No.62/307,229, filed Mar. 11, 2016, Provisional Application No. 62/308,705,filed Mar. 15, 2016, and Provisional Application No. 62/308,743, filedMar. 15, 2016, the entire contents of which are incorporated herein intheir entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to arthroscopic tissue cutting and removaldevices by which anatomical tissues may be cut and removed from a jointor other site. More specifically, this invention relates to instrumentsconfigured for cutting and removing soft tissue with an electrosurgicaldevice.

In several surgical procedures including subacromial decompression,anterior cruciate ligament reconstruction involving notchplasty, andarthroscopic resection of the acromioclavicular joint, there is a needfor cutting and removal of bone and soft tissue. Currently, surgeons usearthroscopic shavers and burrs having rotational cutting surfaces toremove hard tissue in such procedures, and a need had existed forarthroscopic cutters that remove soft tissue rapidly.

Recently, arthroscopic surgical cutters capable of selectively removingboth hard tissues and soft tissues have been developed. Such cutters aredescribed in the following US Patent Publications which are commonlyassigned with the present application: US20130253498; US20160113706;US20160346036; US20160157916; and US20160081737, the full disclosures ofwhich are incorporated herein by reference.

While very effective, it would be desirable to provide arthroscopicsurgical cutters and cutter systems as “reposable” devices withdisposable cutting components and reusable, sterilizable handles.Preferably, the handles would incorporate as many of the high valuesystem components as possible. Further preferably, the handle designswould have a minimum number of external connections to simplifysterilization and set-up. Still more preferably, the cutters and systemswould allow for bipolar cutting as well as monopolar and mechanical(cutting blade) resection. At least some of these objectives will be metby the inventions described herein.

2. Description of the Background Art

Various surgical systems have been disclosed that include a handpieceand/or motor drive that is coupled to a disposable electrosurgicalcutter assembly, including U.S. Pat. Nos. 3,945,375; 4,815,462;5,810,809; 5,957,884; 6,007,553; 6,629,986 6,827,725; 7,112,200 and9,504,521. One commercially available RF shaver sold under the tradenameDYONICS Bonecutter Electroblade Resector (See,http://www.smith-nephew.com/professional/products/all-products/dyonics-bonecutter-electroblade)utilizes an independent or separate RF electrical cable that carriesneither motor power nor electrical signals and couples directly to anexposed part or external surface of the prior art shaver hub. Theelectrical cable must be routed distally in parallel to a reusablehandle. In such a prior art device, the coupling of RF does not extendthrough the reusable handle. The use of Hall effect sensors formonitoring rotational speed of an inner sleeve relative to an outersleeve in an electrosurgical cutter is described in US 2016/0346036 andUS 2017/0027599, both having a common inventor with the presentapplication. Other commonly assigned published US Patent Applicationshave been listed above, including US20130253498; US20160113706;US20160346036; US20160157916; and US20160081737.

SUMMARY OF THE INVENTION

In general, arthroscopic systems according to the present inventioninclude a re-useable, sterilizable handle or handpiece integrated with asingle umbilical cable or conduit. The single umbilical cable or conduitcarries electrical power from a power and/or control console to thehandle for operating both a motor drive unit within the handle and fordelivering the RF power to a disposable RF probe or cutter which may bedetachably connected to the handle. The RF power delivered to the handleand on to the probe or cutter is typically bi-polar, where the handleincludes first and second electrical bi-polar contacts that couple tocorresponding bi-polar electrical contacts on a hub of the disposable RFprobe or cutter that is connected to the handle.

In a first aspect, the present invention provides a disposable bipolarRF probe for use in the presence of an electrically conductive fluid.The probe comprises a shaft including an inner electrically conductivesleeve and an outer electrically conductive sleeve and a hub having acentral passage. Opposing polarity regions of the inner and outerelectrically conductive sleeves are present, typically exposed, in thecentral passage, and the opposing polarity regions have a spacingtherebetween which inhibits intrusion of the conductive fluid and limitsRF or other current flow between said opposing polarity regions when,for example, a distal working end of the probe is immersed in orotherwise in the presence of a conductive fluid during use.

The proximal hub of the disposable bipolar RF probe is typicallyconfigured or adapted for detachable coupling to a handle carrying firstand second electrical contacts for coupling RF current through the hubto said first and second conductive sleeves. The inner and outerelectrically conductive sleeves may be configured to couple RF currentflow to respective first and second opposing polarity electrodes in theworking end of the probe, and the intrusion of conductive fluid isusually limited sufficiently in the interior and central passage of thehub so that RF current flow to the working end is in presence of theconductive fluid is unimpeded.

In specific examples of the disposable bipolar RF probe, at least aportion of the inner electrically conductive sleeve is rotationallydisposed in a bore of the outer electrically conductive sleeve, and saidopposing polarity regions are longitudinally spaced apart in theinterior of the hub by a distance selected to at least substantiallyimpede or limit RF current flow between said opposing polarity regionsduring use. The selected distance is usually at least 0.5 inch, often atleast 0.6 inch, frequently at least 0.8 inch, and sometimes at least 1inch, or longer. The inner and outer sleeves are separated by an annularspace in the hub of usually less than 0.010 inch, often less than 0.004inch, and frequently less than 0.002 inch to further minimize fluidintrusion and maximize electrical resistance between said opposingpolarity regions.

In a second aspect of the present invention, an arthroscopic treatmentsystem comprises a disposable bipolar RF probe as described above and ahandle, where the handle includes a motor drive unit for rotating thesecond conductive sleeve when the disposable bipolar RF probe is coupledto the hub.

In a third aspect of the present invention, a surgical system comprisesa handle carrying a motor drive unit. A disposable RF probe has aproximal hub that detachably couples to the handle, an RF effector, anda component that is driven by the motor drive unit. At least one Hallsensor is carried by or otherwise coupled the motor drive unit toprovide signals representative of motor operating parameters. Acontroller is operatively coupled to the motor and the RF probe by anumbilical conduit that includes (i) an electrical cable for deliveringelectrical power to the motor, (ii) an RF cable for delivering RF powerto the RF effector, and (iii) at least one signal circuit including asignal cable for delivering signals from Hall signals to the controller.Typically, at least one Schmitt trigger operatively coupled to the atleast one signal circuit for reducing noise induction therein.

As used herein, the phrase “Hall effect sensor” refers to a transduceror equivalent analog or digital circuitry that varies its output voltagein response to a magnetic field. Typically, the Hall effect sensoroperates as an analog transducer, directly outputting a voltage signalinduced by the motor drive in the handle to analog or digital circuitryin a controller or other control circuitry in the control console of thepresent invention for the purposes described in detail below.

As used herein, the phrase “Schmitt trigger” refers to a comparatorcircuit with hysteresis implemented by applying positive feedback to thenoninverting input of a comparator or differential amplifier. It is ananalog or digital active circuit which converts an analog input signalto a digital output signal and may be implemented in the controlcircuitry of the systems of the present invention for the purposesdescribed in detail below.

In exemplary embodiments of the surgical systems of the presentinvention, a plurality of Hall sensors are carried by or otherwisecoupled to the handle and the motor drive unit, where each Hall sensorcomprises a signal circuit connected by a signal cable in the umbilicalconduit to the controller. A first Schmitt trigger is located in ahandle end of each signal circuit and a second Schmitt trigger islocated in a controller end of each signal circuit. For example, threeHall sensors may be carried by or otherwise coupled to the handle andthe motor drive unit wherein each of the three Hall sensors comprises asignal circuit connected by a signal cable in the umbilical conduit tothe controller, and a Schmitt trigger may be located in a handle end ofeach of the three signal circuits and another Schmitt trigger may belocated in a controller end of each of the three signal circuits.

In a fourth aspect of the present invention, a surgical system comprisesa handle carrying a motor drive unit including Hall sensors therein. Adisposable RF probe has a proximal hub that detachably couples to thehandle, and the RF probe has an RF effector and a component that isdriven by the motor drive unit. A single umbilical conduit extends fromthe handle to a control console, and the single conduit includes (i) anelectrical cable for delivering electrical power to the motor, (ii) anRF cable for delivering RF power to the RF effector, and (iii) aplurality of signal cables for carrying Hall sensor signals. Thesurgical system may further comprise a first Schmitt trigger coupled toeach signal cable at a handle end thereof and a second Schmitt triggercoupled to each signal cable at a console end thereof.

In a fifth aspect of the present invention, a method of operating anarthroscopic treatment system comprises providing a disposable RFtreatment device detachably coupled to a handle that carries a motordrive unit, where the handle is coupled to a control console through asingle conduit. Power is delivered to the motor and the RF devicethrough first and second respective electrical cables in the singleconduit. A Hall sensor coupled to the motor drive sends motor operatingparameter signals to the control console in a signal circuit includingan electrical cable in the single conduit. At least one Schmitt triggerin the signal circuit reduces noise induction therein due to theproximity of the first and second electrical cables.

In a sixth aspect of the present invention, an arthroscopic systemcomprises a probe having a distal bipolar element and a proximal hubhaving a first polarity electrical contact and a second polarityelectrical contact. A handle having a distal cylindrical passageway isconfigured to removably receive the proximal hub of the probe, and thehub has a first polarity electrical contact and a second polarityelectrical contact. The first polarity electrical contact and the secondpolarity electrical contact on the hub engage the first polarityelectrical contact and the second polarity electrical contact in thepassageway, and the first and second electrical contacts in the distalpassageway of the handle comprise a conductive material which isresistant to alternating current corrosion.

In specific embodiments, the first and second electrical contacts in thedistal passageway of the handle may comprise or are plated with amaterial selected from the group consisting of titanium, gold, silver,platinum, carbon, molybdenum, tungsten, zinc, Inconel, graphite, nickelor a combination thereof. The first and second electrical contacts inthe distal passageway of the handle may be axially spaced-apart andexposed on an inner surface of the distal passageway, where the firstand second electrical contacts may comprise ring-like contacts whichextend circumferentially around at least a portion of the cylindricalpassageway, typically extending 360° around the inner surface of thecylindrical passageway. The arthroscopic systems may further comprise afluid seal between the hub and the cylindrical passageway, where thefluid seal often comprises at least one O-ring disposed on the innersurface of the cylindrical passageway. The fluid seal further mayfurther comprises at least one O-ring disposed on the proximal hub ofthe probe, and at least one of the O-rings is disposed between theaxially spaced apart electrical contacts. Often, at least one O-ring isalso disposed proximally of all of the electrical contacts and at leastone of the O-rings is disposed distally of all of the electricalcontacts.

In other embodiments, the handle carries a motor drive unit with anon-detachable umbilical conduit, where said umbilical conduit carries aplurality of electrical cables. Usually, at least one electrical cableis connected to drive the motor drive unit, at least one cable isconnected to the first polarity electrical contact in the passageway,and at least one cable is connected to the second polarity electricalcontact in the passageway. The umbilical conduit may further carry oneor more electrical cables for signaling and control functions, and thefirst polarity electrical contact and the second polarity electricalcontact on the proximal hub of the probe may comprise spring-loadedelements on an outer surface of the hub.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be discussed withreference to the appended drawings. It should be appreciated that thedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting in scope.

FIG. 1 is a perspective view of a disposable arthroscopic cutter or burrassembly with a ceramic cutting member carried at the distal end of arotatable inner sleeve with a window in the cutting member proximal tothe cutting edges of the burr.

FIG. 2 is an enlarged perspective view of the ceramic cutting member ofthe arthroscopic cutter or burr assembly of FIG. 1.

FIG. 3 is a perspective view of a handle body with a motor drive unit towhich the burr assembly of FIG. 1 can be coupled, with the handle bodyincluding an LCD screen for displaying operating parameters of deviceduring use together with a joystick and mode control actuators on thehandle.

FIG. 4 is an enlarged perspective view of the ceramic cutting membershowing a manner of coupling the cutter to a distal end of the innersleeve of the burr assembly.

FIG. 5A is a cross-sectional view of a cutting assembly similar to thatof FIG. 2 taken along line 5A-5A showing the close tolerance betweensharp cutting edges of a window in a ceramic cutting member and sharplateral edges of the outer sleeve which provides a scissor-like cuttingeffect in soft tissue.

FIG. 5B is a cross-sectional view of the cutting assembly of FIG. 5Awith the ceramic cutting member in a different rotational position thanin FIG. 5A.

FIG. 6 is a perspective view of another ceramic cutting member carriedat the distal end of an inner sleeve with a somewhat rounded distal noseand deeper flutes than the cutting member of FIGS. 2 and 4, and withaspiration openings or ports formed in the flutes.

FIG. 7 is a perspective view of another ceramic cutting member withcutting edges that extend around a distal nose of the cutter togetherwith an aspiration window in the shaft portion and aspiration openingsin the flutes.

FIG. 8 is a perspective view of a ceramic housing carried at the distalend of the outer sleeve.

FIG. 9 is a perspective of another variation of a ceramic member withcutting edges that includes an aspiration window and an electrodearrangement positioned distal to the window.

FIG. 10 is an elevational view of a ceramic member and shaft of FIG. 9showing the width and position of the electrode arrangement in relationto the window.

FIG. 11 is an end view of a ceramic member of FIGS. 9-10 the outwardperiphery of the electrode arrangement in relation to the rotationalperiphery of the cutting edges of the ceramic member.

FIG. 12A is a schematic view of the working end and ceramic cuttingmember of FIGS. 9-11 illustrating a step in a method of use.

FIG. 12B is another view of the working end of FIG. 12A illustrating asubsequent step in a method of use to ablate a tissue surface.

FIG. 12C is a view of the working end of FIG. 12A illustrating a methodof tissue resection and aspiration of tissue chips to rapidly removevolumes of tissue.

FIG. 13A is an elevational view of an alternative ceramic member andshaft similar to that of FIG. 9 illustrating an electrode variation.

FIG. 13B is an elevational view of another ceramic member similar tothat of FIG. 12A illustrating another electrode variation.

FIG. 13C is an elevational view of another ceramic member similar tothat of FIGS. 12A-12B illustrating another electrode variation.

FIG. 14 is a perspective view of an alternative working end and ceramiccutting member with an electrode partly encircling a distal portion ofan aspiration window.

FIG. 15A is an elevational view of a working end variation with anelectrode arrangement partly encircling a distal end of the aspirationwindow.

FIG. 15B is an elevational view of another working end variation with anelectrode positioned adjacent a distal end of the aspiration window.

FIG. 16 is a perspective view of a variation of a working end andceramic member with an electrode adjacent a distal end of an aspirationwindow having a sharp lateral edge for cutting tissue.

FIG. 17 is a perspective view of a variation of a working end andceramic member with four cutting edges and an electrode adjacent adistal end of an aspiration window.

FIG. 18 is perspective view of an arthroscopic system including acontrol and power console, a footswitch and a re-usable motor carrying amotor drive unit.

FIG. 19 is an enlarged sectional view of the distal end of the handle ofFIG. 18 showing first and second electrical contacts therein forcoupling RF energy to a disposable RF probe.

FIG. 20 is a perspective view of a disposable RF probe of the type thatcouples to the re-useable handle of FIGS. 18-19.

FIG. 21 is a sectional perspective view of a proximal hub portion of thedisposable RF probe of FIG. 20.

FIG. 22 is a sectional view of a variation of the hub of FIG. 21 whichincludes a fluid trap for collecting any conductive fluid migratingproximally in the hub.

FIG. 23 is a cross-sectional view of the electrical conduit of FIG. 18taken along line 23-23 of FIG. 18.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to bone cutting and removal devices andrelated methods of use. Several variations of the invention will now bedescribed to provide an overall understanding of the principles of theform, function and methods of use of the devices disclosed herein. Ingeneral, the present disclosure provides for an arthroscopic cutter orburr assembly for cutting or abrading bone that is disposable and isconfigured for detachable coupling to a non-disposable handle and motordrive component. This description of the general principles of thisinvention is not meant to limit the inventive concepts in the appendedclaims.

In general, the present invention provides a high-speed rotating ceramiccutter or burr that is configured for use in many arthroscopic surgicalapplications, including but not limited to treating bone in shoulders,knees, hips, wrists, ankles and the spine. More in particular, thedevice includes a cutting member that is fabricated entirely of aceramic material that is extremely hard and durable, as described indetail below. A motor drive is operatively coupled to the ceramic cutterto rotate the burr edges at speeds ranging from 3,000 rpm to 20,000 rpm.

In one variation shown in FIGS. 1-2, an arthroscopic cutter or burrassembly 100 is provided for cutting and removing hard tissue, whichoperates in a manner similar to commercially available metals shaversand burrs. FIG. 1 shows disposable burr assembly 100 that is adapted fordetachable coupling to a handle 104 and motor drive unit 105 therein asshown in FIG. 3.

The cutter assembly 100 has a shaft 110 extending along longitudinalaxis 115 that comprises an outer sleeve 120 and an inner sleeve 122rotatably disposed therein with the inner sleeve 122 carrying a distalceramic cutting member 125. The shaft 110 extends from a proximal hubassembly 128 wherein the outer sleeve 120 is coupled in a fixed mannerto an outer hub 140A which can be an injection molded plastic, forexample, with the outer sleeve 120 insert molded therein. The innersleeve 122 is coupled to an inner hub 140B (phantom view) that isconfigured for coupling to the motor drive unit 105 (FIG. 3). The outerand inner sleeves 120 and 122 typically can be a thin wall stainlesssteel tube, but other materials can be used such as ceramics, metals,plastics or combinations thereof.

Referring to FIG. 2, the outer sleeve 120 extends to distal sleeveregion 142 that has an open end and cut-out 144 that is adapted toexpose a window 145 in the ceramic cutting member 125 during a portionof the inner sleeve's rotation. Referring to FIGS. 1 and 3, the proximalhub 128 of the burr assembly 100 is configured with a J-lock, snap-fitfeature, screw thread or other suitable feature for detachably lockingthe hub assembly 128 into the handle 104. As can be seen in FIG. 1, theouter hub 140A includes a projecting key 146 that is adapted to matewith a receiving J-lock slot 148 in the handle 104 (see FIG. 3).

In FIG. 3, it can be seen that the handle 104 is operatively coupled byelectrical cable 152 to a controller 155 which controls the motor driveunit 105. Actuator buttons 156 a, 156 b or 156 c on the handle 104 canbe used to select operating modes, such as various rotational modes forthe ceramic cutting member. In one variation, a joystick 158 be movedforward and backward to adjust the rotational speed of the ceramiccutting member 125. The rotational speed of the cutter can continuouslyadjustable, or can be adjusted in increments up to 20,000 rpm. FIG. 3further shows that negative pressure source 160 is coupled to aspirationtubing 162 which communicates with a flow channel in the handle 104 andlumen 165 in inner sleeve 122 which extends to window 145 in the ceramiccutting member 125 (FIG. 2).

Now referring to FIGS. 2 and 4, the cutting member 125 comprises aceramic body or monolith that is fabricated entirely of a technicalceramic material that has a very high hardness rating and a highfracture toughness rating, where “hardness” is measured on a Vickersscale and “fracture toughness” is measured in MPam^(1/2). Fracturetoughness refers to a property which describes the ability of a materialcontaining a flaw or crack to resist further fracture and expresses amaterial's resistance to brittle fracture. The occurrence of flaws isnot completely avoidable in the fabrication and processing of anycomponents.

The authors evaluated technical ceramic materials and tested prototypesto determine which ceramics are best suited for the non-metal cuttingmember 125. When comparing the material hardness of the ceramic cuttersof the invention to prior art metal cutters, it can easily be understoodwhy typical stainless steel bone burrs are not optimal. Types 304 and316 stainless steel have hardness ratings of 1.7 and 2.1, respectively,which is low and a fracture toughness ratings of 228 and 278,respectively, which is very high. Human bone has a hardness rating of0.8, so a stainless steel cutter is only about 2.5 times harder thanbone. The high fracture toughness of stainless steel provides ductilebehavior which results in rapid cleaving and wear on sharp edges of astainless steel cutting member. In contrast, technical ceramic materialshave a hardness ranging from approximately 10 to 15, which is five tosix times greater than stainless steel and which is 10 to 15 timesharder than cortical bone. As a result, the sharp cutting edges of aceramic remain sharp and will not become dull when cutting bone. Thefracture toughness of suitable ceramics ranges from about 5 to 13 whichis sufficient to prevent any fracturing or chipping of the ceramiccutting edges. The authors determined that a hardness-to-fracturetoughness ratio (“hardness-toughness ratio”) is a useful term forcharacterizing ceramic materials that are suitable for the invention ascan be understood form the Chart A below, which lists hardness andfracture toughness of cortical bone, a 304 stainless steel, and severaltechnical ceramic materials.

CHART A Ratio Fracture Hardness Hardness Toughness to Fracture (GPa)(MPam^(1/2)) Toughness Cortical bone 0.8 12  .07:1 Stainless steel 3042.1 228  .01:1 Yttria-stabilized zirconia (YTZP) YTZP 2000 (SuperiorTechnical 12.5 10 1.25:1 Ceramics) YTZP 4000 (Superior Technical 12.5 101.25:1 Ceramics) YTZP (CoorsTek) 13.0 13 1.00:1 Magnesia stabilizedzirconia (MSZ) Dura-Z ® (Superior Technical 12.0 11 1.09:1 Ceramics) MSZ200 (CoorsTek) 11.7 12 0.98:1 Zirconia toughened alumina (ZTA) YTA-14(Superior Technical 14.0 5 2.80:1 Ceramics) ZTA (CoorsTek) 14.8 6 2.47:1Ceria stabilized zirconia CSZ (Superior Technical 11.7 12 0.98:1Ceramics) Silicon Nitride SiN (Superior Technical Ceramics) 15.0 62.50:1

As can be seen in Chart A, the hardness-toughness ratio for the listedceramic materials ranges from 98× to 250× greater than thehardness-toughness ratio for stainless steel 304. In one aspect of theinvention, a ceramic cutter for cutting hard tissue is provided that hasa hardness-toughness ratio of at least 0.5:1, 0.8:1 or 1:1.

In one variation, the ceramic cutting member 125 is a form of zirconia.Zirconia-based ceramics have been widely used in dentistry and suchmaterials were derived from structural ceramics used in aerospace andmilitary armor. Such ceramics were modified to meet the additionalrequirements of biocompatibility and are doped with stabilizers toachieve high strength and fracture toughness. The types of ceramics usedin the current invention have been used in dental implants, andtechnical details of such zirconia-based ceramics can be found inVolpato, et al., “Application of Zirconia in Dentistry: Biological,Mechanical and Optical Considerations”, Chapter 17 in Advances inCeramics—Electric and Magnetic Ceramics, Bioceramics, Ceramics andEnvironment (2011).

In one variation, the ceramic cutting member 125 is fabricated of anyttria-stabilized zirconia as is known in the field of technicalceramics, and can be provided by CoorsTek Inc., 16000 Table MountainPkwy., Golden, Colo. 80403 or Superior Technical Ceramics Corp., 600Industrial Park Rd., St. Albans City, Vt. 05478. Other technicalceramics that may be used consist of magnesia-stabilized zirconia,ceria-stabilized zirconia, zirconia toughened alumina and siliconnitride. In general, in one aspect of the invention, the monolithicceramic cutting member 125 has a hardness rating of at least 8 Gpa(kg/mm²). In another aspect of the invention, the ceramic cutting member125 has a fracture toughness of at least 2 MPam^(1/2).

The fabrication of such ceramics or monoblock components are known inthe art of technical ceramics, but have not been used in the field ofarthroscopic or endoscopic cutting or resecting devices. Ceramic partfabrication includes molding, sintering and then heating the molded partat high temperatures over precise time intervals to transform acompressed ceramic powder into a ceramic monoblock which can provide thehardness range and fracture toughness range as described above. In onevariation, the molded ceramic member part can have additionalstrengthening through hot isostatic pressing of the part. Following theceramic fabrication process, a subsequent grinding process optionallymay be used to sharpen the cutting edges 175 of the burr (see FIGS. 2and 4).

In FIG. 4, it can be seen that in one variation, the proximal shaftportion 176 of cutting member 125 includes projecting elements 177 whichare engaged by receiving openings 178 in a stainless steel split collar180 shown in phantom view. The split collar 180 can be attached aroundthe shaft portion 176 and projecting elements 177 and then laser weldedalong weld line 182. Thereafter, proximal end 184 of collar 180 can belaser welded to the distal end 186 of stainless steel inner sleeve 122to mechanically couple the ceramic body 125 to the metal inner sleeve122. In another aspect of the invention, the ceramic material isselected to have a coefficient of thermal expansion between is less than10 (1×10⁶/° C.) which can be close enough to the coefficient of thermalexpansion of the metal sleeve 122 so that thermal stresses will bereduced in the mechanical coupling of the ceramic member 125 and sleeve122 as just described. In another variation, a ceramic cutting membercan be coupled to metal sleeve 122 by brazing, adhesives, threads or acombination thereof.

Referring to FIGS. 1 and 4, the ceramic cutting member 125 has window145 therein which can extend over a radial angle of about 10° to 90° ofthe cutting member's shaft. In the variation of FIG. 1, the window ispositioned proximally to the cutting edges 175, but in other variations,one or more windows or openings can be provided and such openings canextend in the flutes 190 (see FIG. 6) intermediate the cutting edges 175or around a rounded distal nose of the ceramic cutting member 125. Thelength L of window 145 can range from 2 mm to 10 mm depending on thediameter and design of the ceramic member 125, with a width W of 1 mm to10 mm.

FIGS. 1 and 4 shows the ceramic burr or cutting member 125 with aplurality of sharp cutting edges 175 which can extend helically,axially, longitudinally or in a cross-hatched configuration around thecutting member, or any combination thereof. The number of cutting edges175 ands intermediate flutes 190 can range from 2 to 100 with a flutedepth ranging from 0.10 mm to 2.5 mm. In the variation shown in FIGS. 2and 4, the outer surface or periphery of the cutting edges 175 iscylindrical, but such a surface or periphery can be angled relative toaxis 115 or rounded as shown in FIGS. 6 and 7. The axial length AL ofthe cutting edges can range between 1 mm and 10 mm. While the cuttingedges 175 as depicted in FIG. 4 are configured for optimal bone cuttingor abrading in a single direction of rotation, it should be appreciatedthe that the controller 155 and motor drive 105 can be adapted to rotatethe ceramic cutting member 125 in either rotational direction, oroscillate the cutting member back and forth in opposing rotationaldirections.

FIGS. 5A-5B illustrate a sectional view of the window 145 and shaftportion 176 of a ceramic cutting member 125′ that is very similar to theceramic member 125 of FIGS. 2 and 4. In this variation, the ceramiccutting member has window 145 with one or both lateral sides configuredwith sharp cutting edges 202 a and 202 b which are adapted to resecttissue when rotated or oscillated within close proximity, or inscissor-like contact with, the lateral edges 204 a and 204 b of thesleeve walls in the cut-out portion 144 of the distal end of outersleeve 120 (see FIG. 2). Thus, in general, the sharp edges of window 145can function as a cutter or shaver for resecting soft tissue rather thanhard tissue or bone. In this variation, there is effectively no open gapG between the sharp edges 202 a and 202 b of the ceramic cutting member125′ and the sharp lateral edges 204 a, 204 b of the sleeve 120. Inanother variation, the gap G between the window cutting edges 202 a, 202b and the sleeve edges 204 a, 204 b is less than about 0.020 inch, orless than 0.010 inch.

FIG. 6 illustrates another variation of ceramic cutting member 225coupled to an inner sleeve 122 in phantom view. The ceramic cuttingmember again has a plurality of sharp cutting edges 175 and flutes 190therebetween. The outer sleeve 120 and its distal opening and cut-outshape 144 are also shown in phantom view. In this variation, a pluralityof windows or opening 245 are formed within the flutes 190 andcommunicate with the interior aspiration channel 165 in the ceramicmember as described previously.

FIG. 7 illustrates another variation of ceramic cutting member 250coupled to an inner sleeve 122 (phantom view) with the outer sleeve notshown. The ceramic cutting member 250 is very similar to the ceramiccutter 125 of FIGS. 1, 2 and 4, and again has a plurality of sharpcutting edges 175 and flutes 190 therebetween. In this variation, aplurality of windows or opening 255 are formed in the flutes 190intermediate the cutting edges 175 and another window 145 is provided ina shaft portion 176 of ceramic member 225 as described previously. Theopenings 255 and window 145 communicate with the interior aspirationchannel 165 in the ceramic member as described above.

It can be understood that the ceramic cutting members can eliminate thepossibility of leaving metal particles in a treatment site. In oneaspect of the invention, a method of preventing foreign particle inducedinflammation in a bone treatment site comprises providing a rotatablecutter fabricated of a ceramic material having a hardness of at least 8Gpa (kg/mm²) and/or a fracture toughness of at least 2 MPam^(1/2) androtating the cutter to cut bone without leaving any foreign particles inthe treatment site. The method includes removing the cut bone tissuefrom the treatment site through an aspiration channel in a cuttingassembly.

FIG. 8 illustrates variation of an outer sleeve assembly with therotating ceramic cutter and inner sleeve not shown. In the previousvariations, such as in FIGS. 1, 2 and 6, shaft portion 176 of theceramic cutter 125 rotates in a metal outer sleeve 120. FIG. 8illustrates another variation in which a ceramic cutter (not shown)would rotate in a ceramic housing 280. In this variation, the shaft or aceramic cutter would thus rotate is a similar ceramic body which may beadvantageous when operating a ceramic cutter at high rotational speeds.As can be seen in FIG. 8, a metal distal metal housing 282 is welded tothe outer sleeve 120 along weld line 288. The distal metal housing 282is shaped to support and provide strength to the inner ceramic housing282.

FIGS. 9-11 are views of an alternative tissue resecting assembly orworking end 400 that includes a ceramic member 405 with cutting edges410 in a form similar to that described previously. FIG. 9 illustratesthe monolithic ceramic member 405 carried as a distal tip of a shaft orinner sleeve 412 as described in previous embodiments. The ceramicmember 405 again has a window 415 that communicates with aspirationchannel 420 in shaft 412 that is connected to negative pressure source160 as described previously. The inner sleeve 412 is operatively coupledto a motor drive 105 and rotates in an outer sleeve 422 of the typeshown in FIG. 2. The outer sleeve 422 is shown in FIG. 10.

In the variation illustrated in FIG. 9, the ceramic member 405 carriesan electrode arrangement 425, or active electrode, having a singlepolarity that is operatively connected to an RF source 440. A returnelectrode, or second polarity electrode 430, is provided on the outersleeve 422 as shown in FIG. 10. In one variation, the outer sleeve 422can comprise an electrically conductive material such as stainless steelto thereby function as return electrode 445, with a distal portion ofouter sleeve 422 is optionally covered by a thin insulating layer 448such as parylene, to space apart the active electrode 425 from thereturn electrode 430.

The active electrode arrangement 425 can consist of a single conductivemetal element or a plurality of metal elements as shown in FIGS. 9 and10. In one variation shown in FIG. 9, the plurality of electrodeelements 450 a, 450 b and 450 c extend transverse to the longitudinalaxis 115 of ceramic member 405 and inner sleeve 412 and are slightlyspaced apart in the ceramic member. In one variation shown in FIGS. 9and 10, the active electrode 425 is spaced distance D from the distaledge 452 of window 415 which is less than 5 mm and often less than 2 mmfor reasons described below. The width W and length L of window 415 canbe the same as described in a previous embodiment with reference to FIG.4.

As can be seen in FIGS. 9 and 11, the electrode arrangement 425 iscarried intermediate the cutting edges 410 of the ceramic member 405 ina flattened region 454 where the cutting edges 410 have been removed. Ascan be best understood from FIG. 11, the outer periphery 455 of activeelectrode 425 is within the cylindrical or rotational periphery of thecutting edges 410 when they rotate. In FIG. 11, the rotational peripheryof the cutting edges is indicated at 460. The purpose of the electrode'souter periphery 455 being equal to, or inward from, the cutting edgeperiphery 460 during rotation is to allow the cutting edges 410 torotate at high RPMs to engage and cut bone or other hard tissue withoutthe surface or the electrode 425 contacting the targeted tissue.

FIG. 9 further illustrates a method of fabricating the ceramic member405 with the electrode arrangement 425 carried therein. The moldedceramic member 405 is fabricated with slots 462 that receive theelectrode elements 450 a-450 c, with the electrode elements fabricatedfrom stainless steel, tungsten or a similar conductive material. Eachelectrode element 450 a-450 c has a bore 464 extending therethrough forreceiving an elongated wire electrode element 465. As can be seen inFIG. 9, and the elongated wire electrode 465 can be inserted from thedistal end of the ceramic member 405 through a channel in the ceramicmember 405 and through the bores 464 in the electrode elements 450 a-450c. The wire electrode 465 can extend through the shaft 412 and iscoupled to the RF source 440. The wire electrode element 465 thus can beused as a means of mechanically locking the electrode elements 450 a-450c in slots 462 and also as a means to deliver RF energy to the electrode425.

Another aspect of the invention is illustrated in FIGS. 9-10 wherein itcan be seen that the electrode arrangement 425 has a transversedimension TD relative to axis 115 that is substantial in comparison tothe window width W as depicted in FIG. 10. In one variation, theelectrode's transverse dimension TD is at least 50% of the window widthW, or the transverse dimension TD is at least 80% of the window width W.In the variation of FIGS. 9-10, the electrode transverse dimension TD is100% or more of the window width W. It has been found that tissue debrisand byproducts from RF ablation are better captured and extracted by awindow 415 that is wide when compared to the width of the RF plasmaablation being performed.

In general, the tissue resecting system comprises an elongated shaftwith a distal tip comprising a ceramic member, a window in the ceramicmember connected to an interior channel in the shaft and an electrodearrangement in the ceramic member positioned distal to the window andhaving a width that is at 50% of the width of the window, at 80% of thewidth of the window or at 100% of the width of the window. Further, thesystem includes a negative pressure source 160 in communication with theinterior channel 420.

Now turning to FIGS. 12A-12C, a method of use of the resecting assembly400 of FIG. 9 can be explained. In FIG. 12A, the system and a controlleris operated to stop rotation of the ceramic member 405 in a selectedposition were the window 415 is exposed in the cut-out 482 of the openend of outer sleeve 422 shown in phantom view. In one variation, acontroller algorithm can be adapted to stop the rotation of the ceramic405 that uses a Hall sensor 484 a in the handle 104 (see FIG. 3) thatsenses the rotation of a magnet 484 b carried by inner sleeve hub 140Bas shown in FIG. 2. The controller algorithm can receive signals fromthe Hall sensor which indicated the rotational position of the innersleeve 412 and ceramic member relative to the outer sleeve 422. Themagnet 484 b can be positioned in the hub 140B (FIG. 2) so that whensensed by the Hall sensor, the controller algorithm can de-activate themotor drive 105 so as to stop the rotation of the inner sleeve in theselected position.

Under endoscopic vision, referring to FIG. 12B, the physician then canposition the electrode arrangement 425 in contact with tissue targeted Tfor ablation and removal in a working space filled with fluid 486, suchas a saline solution which enables RF plasma creation about theelectrode. The negative pressure source 160 is activated prior to orcontemporaneously with the step of delivering RF energy to electrode425. Still referring to FIG. 12B, when the ceramic member 405 ispositioned in contact with tissue and translated in the direction ofarrow Z, the negative pressure source 160 suctions the targeted tissueinto the window 415. At the same time, RF energy delivered to electrodearrangement 425 creates a plasma P as is known in the art to therebyablate tissue. The ablation then will be very close to the window 415 sothat tissue debris, fragments, detritus and byproducts will be aspiratedalong with fluid 486 through the window 415 and outwardly through theinterior extraction channel 420 to a collection reservoir. In one methodshown schematically in FIG. 12B, a light movement or translation ofelectrode arrangement 425 over the targeted tissue will ablate a surfacelayer of the tissue and aspirate away the tissue detritus.

FIG. 12C schematically illustrates a variation of a method which is ofparticular interest. It has been found if suitable downward pressure onthe working end 400 is provided, then axial translation of working end400 in the direction arrow Z in FIG. 12C, together with suitablenegative pressure and the RF energy delivery will cause the plasma P toundercut the targeted tissue along line L that is suctioned into window415 and then cut and scoop out a tissue chips indicated at 488. Ineffect, the working end 400 then can function more as a high volumetissue resecting device instead of, or in addition to, its ability tofunction as a surface ablation tool. In this method, the cutting orscooping of such tissue chips 488 would allow the chips to be entrainedin outflows of fluid 486 and aspirated through the extraction channel420. It has been found that this system with an outer shaft diameter of7.5 mm, can perform a method of the invention can ablate, resect andremove tissue greater than 15 grams/min, greater than 20 grams/min, andgreater than 25 grams/min.

In general, a method corresponding to the invention includes providingan elongated shaft with a working end 400 comprising an active electrode425 carried adjacent to a window 415 that opens to an interior channelin the shaft which is connected to a negative pressure source,positioning the active electrode and window in contact with targetedtissue in a fluid-filled space, activating the negative pressure sourceto thereby suction targeted tissue into the window and delivering RFenergy to the active electrode to ablate tissue while translating theworking end across the targeted tissue. The method further comprisesaspirating tissue debris through the interior channel 420. In a method,the working end 400 is translated to remove a surface portion of thetargeted tissue. In a variation of the method, the working end 400 istranslated to undercut the targeted tissue to thereby remove chips 488of tissue.

Now turning to FIGS. 13A-13C, other distal ceramic tips of cuttingassemblies are illustrated that are similar to that of FIGS. 9-11,except the electrode configurations carried by the ceramic members 405are varied. In FIG. 13A, the electrode 490A comprises one or moreelectrode elements extending generally axially distally from the window415. FIG. 13B illustrates an electrode 490B that comprises a pluralityof wire-like elements 492 projecting outwardly from surface 454. FIG.13C shows electrode 490C that comprises a ring-like element that ispartly recessed in a groove 494 in the ceramic body. All of thesevariations can produce an RF plasma that is effective for surfaceablation of tissue, and are positioned adjacent to window 415 to allowaspiration of tissue detritus from the site.

FIG. 14 illustrates another variation of a distal ceramic tip 500 of aninner sleeve 512 that is similar to that of FIG. 9 except that thewindow 515 has a distal portion 518 that extends distally between thecutting edges 520, which is useful for aspirating tissue debris cut byhigh speed rotation of the cutting edges 520. Further, in the variationof FIG. 14, the electrode 525 encircles a distal portion 518 of window515 which may be useful for removing tissue debris that is ablated bythe electrode when the ceramic tip 500 is not rotated but translatedover the targeted tissue as described above in relation to FIG. 12B. Inanother variation, a distal tip 500 as shown in FIG. 14 can be energizedfor RF ablation at the same time that the motor drive rotates back andforth (or oscillates) the ceramic member 500 in a radial arc rangingfrom 1° to 180° and more often from 10° to 90°.

FIGS. 15A-15B illustrate other distal ceramic tips 540 and 540′ that aresimilar to that of FIG. 14 except the electrode configurations differ.In FIG. 15A, the window 515 has a distal portion 518 that again extendsdistally between the cutting edges 520, with electrode 530 comprising aplurality of projecting electrode elements that extend partly around thewindow 515. FIG. 15B shows a ceramic tip 540′ with window 515 having adistal portion 518 that again extends distally between the cutting edges520. In this variation, the electrode 545 comprises a single bladeelement that extends transverse to axis 115 and is in close proximity tothe distal end 548 of window 515.

FIG. 16 illustrates another variation of distal ceramic tip 550 of aninner sleeve 552 that is configured without the sharp cutting edges 410of the embodiment of FIGS. 9-11. In other respects, the arrangement ofthe window 555 and the electrode 560 is the same as describedpreviously. Further, the outer periphery of the electrode is similar tothe outward surface of the ceramic tip 550. In the variation of FIG. 16,the window 555 has at least one sharp edge 565 for cutting soft tissuewhen the assembly is rotated at a suitable speed from 500 to 5,000 rpm.When the ceramic tip member 550 is maintained in a stationary positionand translated over targeted tissue, the electrode 560 can be used toablate surface layers of tissue as described above.

FIG. 17 depicts another variation of distal ceramic tip 580 coupled toan inner sleeve 582 that again has sharp burr edges or cutting edges 590as in the embodiment of FIGS. 9-11. In this variation, the ceramicmonolith has only 4 sharp edges 590 which has been found to work wellfor cutting bone at high RPMs, for example from 8,000 RPM to 20,000 RPM.In this variation, the arrangement of window 595 and electrode 600 isthe same as described previously. Again, the outer periphery ofelectrode 595 is similar to the outward surface of the cutting edges590.

FIGS. 18-21 illustrate components of an arthroscopic system 800including a re-usable handle 804 that is connected by a single umbilicalcable or conduit 805 to a controller unit or console 810. Further, afootswitch 812 is connected by cable 814 to the console 810 foroperating the system. As can be seen in FIGS. 18 and 20, the handle 804is adapted to receive a proximal housing or hub 820 of a disposable RFshaver or probe 822 with RF functionality of the types shown in FIGS.9-17 above.

In one variation, the console 810 of FIG. 18 includes an electricalpower source 825 for operating the motor drive unit 828 in the handle804, an RF power supply or source 830 for delivering RF energy to the RFelectrodes of the disposable RF cutter or shaver 822, and dualperistaltic pumps 835A and 835B for operating the fluid managementcomponent of the system. The console 810 further carries amicroprocessor or controller 838 with software to operate and integrateall the motor drive, control, and RF functionality of the system. As canbe seen in FIG. 18, a disposable cassette 840 carries inflow tubing 842a and outflow tubing 842 b that cooperate with inflow and outflowperistaltic pumps in the console 810. The footswitch 812 in onevariation includes switches for operating the motor drive unit 828, foroperating the RF probe in a cutting mode with radiofrequency energy, andfor operating the RF probe in a coagulation mode.

Of particular interest, the system of the invention includes a handle804 with first and second electrical contacts 845A and 845B, typicallyring-like contacts that form a continuous conductive path circumscribingan inner wall of a receiving passageway 846 of handle 804 (see FIG. 19)that cooperate with electrical contacts 850A and 850B in the proximalhub 820 of the disposable RF shaver 822 (see FIGS. 20-21). Inparticular, when the proximal hub 820 is fully inserted into thereceiving passageway 846, the electrical contacts 850A and 850B will beaxially or longitudinally aligned with the electrical contacts 845A and845B to provide a conductive path to provide RF power from theelectrical power source 825 to outer and inner sleeves 870 and 875 of aRF shaver 822, respectively, as will be described further below. Theproximal hub 820 can be inserted into the receiving passageway 846without regard to rotational orientation so that a user can align aworking end 856 of a shaft portion 855 of the shaver 822 in any desiredrelative rotational orientation.

The RF shaver 822 includes the shaft portion 855 that extends to theworking end 856 that carries a bi-polar electrode arrangement, of thetype shown in FIGS. 9-17. Handle embodiment 804 provides all wiring andcircuitry necessary for connecting the RF shaver 822 to the controller810 within the single umbilical cable or conduit 805 that extendsbetween handle 804 and the console 810. For example, the conduit 805typically carries electrical power leads for a three-phase motor driveunit 828 in the handle 804, electrical power leads from the RF powersupply or source 830 to the handle as well as a number of electricalsignal leads for Hall and/or other sensors in the motor drive unit 828that allow the controller 838 to control the operating parameters of themotor drive 828. In this embodiment, the handle 804 and the conduit 805are a single component that can be easily sterilized, which isconvenient for operating room personnel and economical for hospitals. Ascan be understood from FIG. 18, the single umbilical cable or conduit805 is not detachable from the handle 804. In other embodiments, thesingle umbilical cable or conduit 805 may be detachable from the handle804.

As described previously with respect to FIGS. 12A-12C, the RF cutter orshaver 22 will typically be connectable to a vacuum or negative pressuresource. Preferably, the handle 804 will include a suction port 972 whichcan be detachably or removably connected to a vacuum or suction line 974(shown in broken line). A suction lumen 970 extends axially orlongitudinally through the handle and has a distal section 976 whichconnects to the receiving passageway 846 so that a suction or vacuum canbe drawn in an inner lumen 875 a of the inner sleeve 875 in order toaspirate fluid through the RF shaver when the shaver is connected to thehandle, as described elsewhere herein. As a result of this pathway, theelectrical contacts 850A and 850B and electrical contacts 845A and 845Bmay be exposed to the electrically conductive fluids which is beingaspirated through the handle. Design aspects of the handle 804 and hub820 which reduce or eliminate the risk of electrical shorting and/orcorrosion resulting from such exposure are described below.

One commercially available RF shaver sold under the tradename DYONICSBonecutter Electroblade Resector (See,http://www.smith-nephew.com/professional/products/all-products/dyonics-bonecutter-electroblade)utilizes an independent or separate RF electrical cable that carriesneither motor power nor electrical signals and couples directly to anexposed part or external surface of the prior art shaver hub. Theelectrical cable must be routed distally in parallel to a reusablehandle. In such a prior art device, the coupling of RF does not extendthrough the reusable handle.

The present invention employs a unitary umbilical cable or conduit 805for coupling the handle 804 to console 810, as shown in FIG. 18. RFpower from the handle is supplied to the disposable RF shaver 822 asshown in FIGS. 21-23. The systems of the present invention incorporate anumber of innovations for (i) coupling RF energy through the handle tothe RF shaver, and (ii) in eliminating electrical interference amongsensitive, low power Hall sensor signals and circuitry and the higherpower current flows to the motor drive unit 828 and to the RF probe 822.

In one aspect of the invention, referring to FIG. 19, the electricalcontacts 845A and 845B are ring-like, e.g. cylindrical or partlycylindrical, typically extending around the inner surface or wall of thereceiving passageway 846 of the handle 804. In use, the electricalcontacts 845A and 845B will be exposed to electrically conductive fluidsand that are aspirated through the probe 822 and outflow passageway orlumen 970 of the handle 804, subjecting the electrical contacts 845A and845B to alternating current corrosion, which is also known as straycurrent corrosion, which terms will be used interchangeably herein.Typically, stainless steel would be used for such electrical contacts.However, it has been found that stainless steel electrical contactswould have a very short lifetime in this application due to corrosionduring use. As can be understood from FIGS. 19 and 21, the more proximalcylindrical electrical contact 845B in passageway 846 which engageselectrical contact 850B in the hub 820 will be exposed fluid outflows,and thus subject to corrosion. The more distal electrical contact 845Ain passageway 846 which engages electrical contact 850A in hub 820 issealed from fluid outflows by O-ring 854 (FIG. 21), but typically theexchange of probes in the handle 804 during a procedure will expose theelectrical contact 845A to some conductive fluid which again will resultin corrosion,

In this application, if stainless steel electrical contacts were used,RF alternating currents that would pass between such stainless steelcontact surfaces would consist of a blend of capacitive and resistivecurrent. The resistance between the contacting surfaces of the contactsis referred to as the polarization resistance, which is thetransformation resistance that converts electron conductance intocurrent conductance while capacitance makes up the electrochemical layerof the stainless steel surface. The capacitive portion of the currentdoes not lead to corrosion, but causes reduction and oxidation ofvarious chemical species on the metal surface. The resistive part of thecurrent is the part that causes corrosion in the same manner as directcurrent corrosion. The association between the resistive and capacitivecurrent components is known in alternating current corrosion and suchresistance currents can leads to very rapid corrosion.

In one aspect of the invention, to prevent such alternating currentcorrosion, the electrical contacts 845A and 845B (FIG. 19) in thereceiving passageway 846 of the handle 804 comprise materials thatresist such corrosion, preferably biocompatible corrosion-resistantmaterials. By “biocompatible,” it is meant that the materials regenerally biologically inert and will not cause adverse reactions whenexposed to body tissues and fluids under the conditions describedherein. In one variation, the first and second electrical contacts 845Aand 845B in handle 804 comprise a conductive material selected from thegroup of titanium, gold, silver, platinum, carbon, molybdenum, tungsten,zinc, Inconel, graphite, nickel or a combination thereof. The first andsecond electrical contacts 845A and 845B are spaced apart by at least0.04 inch, often at least 0.08 inch, and sometimes at least 0.16 inch.Such electrical contacts can extend radially at least partly around thecylindrical passageway, or can extend in 360° around the cylindricalpassageway 846. The contacts 850A and 850B on the hub 820 can be formedfrom the same materials but since the disposable RF cutter 822,corrosion is less problematic, so contacts 850A and 850B can also beformed from other materials which are less resistant to alternatingcurrent corrosion, such as stainless steel.

In another aspect of the invention, the motor shaft 860 (FIG. 19) willalso be exposed to conductive fluids and subject to alternative currentcorrosion. For this reason, the motor shaft 860 and exposed portions ofmotor drive unit 828 are comprised of or are plated with, one of thecorrosion resistant materials listed above. In one variation, the motorshaft 860 and exposed motor drive components have a surface plating ofmolybdenum.

In another aspect of the invention, the receiving passageway 846 of thehandle 804 includes an O-ring 852 or other fluid seal between the hub820 and passageway 846, as shown in FIG. 19. Additionally oralternatively, one or more O-rings 854 and 857 or other fluid seals canbe carried by the hub 820, as shown in FIG. 21. As can be seen in FIG.21, one such O-ring 854 can be positioned between the first and secondelectrical contacts 845A and 845B in the hub 820 and 850A and 850B inthe handle to inhibit or prevent any passage of fluid therebetween toreduce the risk of shorting. The second such O-ring 857 can bepositioned distally of the electrical contacts, so that together withthe O-ring 852 on the receiving passageway 846, seals are provide onproximal and distal sides of the electrical contacts to prevent orinhibit fluid intrusion into annular space between the hub 820 and thesurface of passageway 846.

Referring now to FIGS. 20 and 21, another aspect of the inventionrelates to designs and mechanisms for effectively coupling RF energyfrom RF power supply or source 830 (FIG. 18) to the working end 856 ofthe RF probe or cutter 822 through two thin-wall concentric, conductivesleeves 870 and 875 that are assembled into a shaft 855 of the RF probe.

FIG. 21 is an enlarged sectional view of the hub 820 of RF probe 822which illustrates the components and electrical pathways that enable RFdelivery to the probe working end 856. In particular, the shaft 855comprises an outer sleeve 870 and a concentric inner sleeve 875 that isrotationally disposed in a bore or longitudinal passageway 877 of theouter sleeve 870. Each of the outer sleeve 870 and inner sleeve 875comprise a thin-wall electrically conductive metal sleeve which carry RFcurrent to and from spaced-apart opposing polarity electrodes in theworking end 856. As shown in FIG. 21, the inner sleeve 875 provides anelectrically conductive path or conductor to an active electrode in theworking end 856, such as a rotatable shaver component as shown, forexample, in FIG. 17. In FIG. 21, the outer sleeve 870 is fixed andstationary relative to the hub 820 and has a distal end or region thatcomprises or serves as a local return or dispersive electrode as isknown in the art. A working end with an active electrode and adispersive or return electrode both located on the cutter or probe willbe considered a “bipolar” configuration in contrast to “monopolar”devices which rely on a remote ground or dispersive electrode connectedseparately to a RF power supply.

As can be seen in FIG. 21, the outer and inner sleeves, 870 and 875, areseparated by insulator layers as will be described below. A proximal end880 of outer sleeve 870 is fixed in the hub 820, for example comprisingan electrically non-conductive, plastic material molded over the hub820. In FIG. 21, a proximal end 882 of the inner sleeve 875 is similarlyfixed in a molded plastic coupler 862 that is adapted to mate with adistal end of the shaft 860 of motor drive unit 828 (FIG. 18), typicallyhaving spines or other coupling elements to assure sufficient coupling.Thus, the assembly of inner sleeve 875 and the coupler 862 is configuredto rotate within a passageway 885 in the hub 820 and within the bore orlongitudinal passageway of outer sleeve 870.

The outer sleeve 870 has an exterior insulating layer 890, such as aheat shrink polymer, that extends distally from hub 820 over the shaft855. The inner sleeve 875 similarly has a heat shrink polymer layer 892over it outer surface which electrically isolates or separates the innersleeve 875 from the outer sleeve 870 throughout the length of the shaft855.

The electrical pathways from the handle 804 to the outer and innersleeves 870 and 875 are established by the first or proximal-most,spring-loaded electrical contact 850A disposed on an exterior surface ofhub 820. The electrical contact 850A is configured to engage thecorresponding electrical contact 845A in the handle 804, as shown inFIG. 19 when the hub 820 is fully received in the passageway 846 (FIGS.18 and 19). The electrical contact 850A is connected and electricallycoupled to an electrically conductive core component 895 within the hub820 that in turn is electrically coupled to a proximal end 880 of theouter sleeve 870.

FIG. 21 further shows a second spring-loaded electrical contact 850B inhub 820 that is adapted to deliver RF current to the rotating innersleeve 875. In FIG. 21, the electrical contact 850B has a spring-loadedinterior portion 896 that engages a collar 890 which in turn is coupledto the inner sleeve 875 and the coupler 862.

Referring still to FIG. 21, an assembly of the hub assembly 820 and theouter sleeve 870 defines a first, proximal-most electrical region,herein called a first polarity region 900A, that is electricallyconductively exposed to (i.e. not electrically isolated from) aninterior space of the passageway. Similarly, an assembly of the innersleeve 875 and a collar 890 defines a second polarity region 900B thatis electrically conductively exposed to the passageway 885 extendingthrough hub 820.

As the working end 856 of the RF probe or cutter 822 will be immersed aconductive saline or other solution during use, the conductive solutionwill inevitably migrate, typically by capillary action, in a proximalthrough an annular space 885 between an inner wall of the bore orlongitudinal passageway 877 and an outer wall of the insulator layer 892over inner sleeve 875. Although this annular space or passageway 885 isvery small, saline solution still will migrate over the duration of anarthroscopic procedure, which can be from 5 minutes to an hour or more.As can be understood from FIG. 21, the saline can eventually migrate toform an electrically conductive path or bridge between the first andsecond opposing polarity regions 900A and 900B. Such bridging wouldcause a short circuit and disrupt RF current flow between the workingend 856 and the RF power supply or source 830. Even if the short-circuitcurrent flow through between regions 900A and 900B is very low and doesnot stop treatment, it could still cause unwanted heating in interior ofhub 820. Thus, it is desirable to limit or eliminate any potential RFcurrent flow between the first and second opposing polarity regions 900Aand 900B through the passageway 885 in hub 820.

In one embodiment intended to eliminate such short-circuit RF currentflow, shown in FIG. 21, a longitudinal or axial dimension AD between thefirst and second opposing polarity regions 900A and 900B is selected tobe large enough to provide a very high electrical resistance (resistanceis proportional to length of the potentially conductive path) in orderto substantially or entirely prevent electrical current flow betweenregions 900A and 900B due. In a variation, the axial dimension AD is atleast 0.5 inch, at least 0.6 inch, at least 0.8 inch or at least 1 inch.In such a variation, it is also important to limit the radial dimensionof the annular space or gap 905 between the inner and outer sleeves 870and 875, which can further increases resistance (resistance is inverselyproportion to the cross-sectional area of the potential conductive path)to current flow between the first and second opposing polarity regions900A and 900B. In specific embodiments, the annular gap 905 can have aradial width or dimension of less than 0.006 inch, less than 0.004 inch,or less than 0.002 inch, typically being in a range from 0.001 inch to0.006 inch, often being in a range from 0.001 inch to 0.004 inch, andsometimes being in a range from 0.001 inch to 0.002 inch. By providingthe selected axial dimension AD and radial dimension of the annular gap905, the potential electrical pathway in a conductive fluid inpassageway 885 and any potential unwanted current flow can besubstantially reduced and often eliminated.

In other embodiments, other structure or modifications can be providedto reduce or eliminate the amount of conductive saline solutionmigrating through the annular gap 905 between the opposing polarityregions 900A and 900B. For example, FIG. 22 show an embodiment in whichan enlarged annular or partly annular space or fluid trap 908 isprovided to allow saline to flow into the space 908 by gravity andcollect therein. Such a space will prevent or “break” the capillaryaction from assisting in the proximal migration of a conductive fluid inpassageway 885. In a similar embodiment, still referring to FIG. 22, oneor more apertures 910 can be provided in hub 820 to allow any saline intrap 908 to fall outwardly and be removed from the handle 804. Inanother variation, a desiccant material (not shown) can be exposed tothe space 908 to absorb a conductive liquid and thus prevent anelectrically conductive pathway between the first and second opposingpolarity regions 900A and 900B (see FIG. 22).

As described above, the single umbilical cable or conduit 805 thatextends from the handle 804 to console 810 includes multiple electricalcables, wires, or other electrical conductors for powering and operatingthe motor drive unit 828, for delivering RF energy to the RF probe 822and for other signaling and control functions as described below. FIG.23 shows a cross-section of the conduit 805 of FIG. 18.

The single umbilical cable or conduit 805 carries a motor power cable915 and a RF bipolar cable 916. Cables 920 are provided for power andground to a circuit board in handle 804. Cable 922 is connected to aHall sensor (not shown) in handle 804 which detects the rotationalposition of a magnetic element 924 on coupler 862 (see FIG. 21) whichallows the controller to sense the rotational position of coupler 862and inner sleeve 875 relative to the hub 820. Electrical cable 925 iscoupled to the LCD screen 926 in the handle 804 (FIG. 18). Cablesindicated at 930 are coupled to the joystick 935 and actuator buttons936 in the handle 804 as shown in FIG. 18. Finally, a cable 940 hasthree electrical leads 942 a, 942 b and 942 c that are coupled to threeHall sensors 945 a, 945 b and 945 b in the motor drive unit 828 (FIG.18) which are adapted to provide signals relating to operatingparameters of the motor.

As can be seen in FIG. 18, an interface circuit board 948 in handle 804carries three Schmitt triggers 950 a, 950 b and 950 c to reduce noiseinduction on the three independent Hall sensor circuits 945 a, 945 b,and 945 c that are integrated into the three-phase motor 828 in thehandle 804. In use, a high fidelity of signals from the Hall sensors 945a, 945 b and 945 b is essential for controlling the speed and therotational direction of the three-phase motor. Thus, the three Schmitttriggers 950 a, 950 b and 950 c reduce such noise generated by thethree-phase motor.

As signals from the Hall sensors 945 a, 945 b and 945 b travel over thelength of the cables 942 a, 942 b and 942 c (see FIG. 23), such signalswill couple with the three-phase motor power signals in conduit 805 aswell as coupling with RF signals in conduit 805 during use of the RFprobe. For this reason, three more Schmitt triggers 960 a, 960 b and 960c are provided inside the console 810 between the console ends of theHall sensor circuits and the three-phase motor control circuit (FIG.18). The role of these three Schmitt triggers 960 a, 960 b and 960 c isto remove this coupled noise before the Hall sensor signals can berouted to control circuitry that controls the three-phase motor 828.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration and the above description of theinvention is not exhaustive. Specific features of the invention areshown in some drawings and not in others, and this is for convenienceonly and any feature may be combined with another in accordance with theinvention. A number of variations and alternatives will be apparent toone having ordinary skills in the art. Such alternatives and variationsare intended to be included within the scope of the claims. Particularfeatures that are presented in dependent claims can be combined and fallwithin the scope of the invention. The invention also encompassesembodiments as if dependent claims were alternatively written in amultiple dependent claim format with reference to other independentclaims.

Other variations are within the spirit of the present invention. Thus,while the invention is susceptible to various modifications andalternative constructions, certain illustrated embodiments thereof areshown in the drawings and have been described above in detail. It shouldbe understood, however, that there is no intention to limit theinvention to the specific form or forms disclosed, but on the contrary,the intention is to cover all modifications, alternative constructions,and equivalents falling within the spirit and scope of the invention, asdefined in the appended claims.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. The term “connected” is to beconstrued as partly or wholly contained within, attached to, or joinedtogether, even if there is something intervening. Recitation of rangesof values herein are merely intended to serve as a shorthand method ofreferring individually to each separate value falling within the range,unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate embodiments of the invention and does not pose a limitationon the scope of the invention unless otherwise claimed. No language inthe specification should be construed as indicating any non-claimedelement as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.

What is claimed is:
 1. A disposable bipolar RF probe for use in thepresence of an electrically conductive fluid, the disposable bipolar RFprobe comprising: a shaft including an inner electrically conductivesleeve with a first polarity region at a proximal end thereof and anouter electrically conductive sleeve with a second polarity region at aproximal end thereof, wherein the inner electrically conductive sleeveis concentrically received within the outer electrically conductivesleeve along a longitudinal axis, and a proximal hub including a centralpassage, wherein the respective proximal ends of the inner and outerelectrically conductive sleeves are received in the central passage suchthat the first polarity region and the second polarity region areexposed in the central passage and are axially separated from each otherin the central passage by an annular space that extends fully from thefirst polarity region to the second polarity region in the centralpassage, wherein said annular space is open to fluid flow from the firstpolarity region to the second polarity region to allow the electricallyconductive fluid to migrate in a proximal direction through the annularspace from the first polarity region to the second polarity region yethas a longitudinal length and a radial dimension selected to achieve anelectrical resistance of the electrically conductive fluid along theannular space for limiting current flow between the first polarityregion and the second polarity region in the presence of electricallyconductive fluid during use.
 2. The disposable bipolar RF probe of claim1, wherein the inner electrically conductive sleeve is configured tocouple RF current flow to a first electrode having a first polarity in aworking end of the probe, and the outer electrically conductive sleeveis configured to couple RF current flow to a second electrode having asecond polarity in the working end of the probe, the first polarity andthe second polarity opposing one another.
 3. The disposable bipolar RFprobe of claim 2, wherein said electrical resistance in the presence ofelectrically conductive fluid during use is achieved sufficiently sothat RF current flow to the working end is unimpeded.
 4. The disposablebipolar RF probe of claim 1, wherein at least a portion of the innerelectrically conductive sleeve is rotationally disposed in a bore of theouter electrically conductive sleeve.
 5. The disposable bipolar RF probeof claim 1, wherein the longitudinal length is at least 0.5 inch.
 6. Thedisposable bipolar RF probe of claim 5, wherein the radial dimension isless than 0.010 inch.
 7. The disposable bipolar RF probe of claim 1,wherein the proximal hub is adapted for detachable coupling to a handlecarrying first and second electrical contacts for coupling RF currentthrough the proximal hub to said inner and outer electrically conductivesleeves, respectively.
 8. A system comprising: the disposable bipolar RFprobe of claim 1; and a handle, wherein the handle includes a motordrive unit for rotating the inner electrically conductive sleeve whenthe disposable bipolar RF probe is coupled to the handle.
 9. Thedisposable bipolar RF probe of claim 1, wherein the longitudinal lengthis at least 0.6 inch.
 10. The disposable bipolar RF probe of claim 9,wherein the radial dimension is less than 0.004 inch.
 11. The disposablebipolar RF probe of claim 9, wherein the radial dimension is less than0.002 inch.
 12. The disposable bipolar RF probe of claim 1, wherein thelongitudinal length is at least 0.8 inch.
 13. The disposable bipolar RFprobe of claim 1, wherein the longitudinal length is at least 1.0 inch.14. The disposable bipolar RF probe of claim 13, wherein the radialdimension is in the range of 0.001 inch to 0.002 inch.